OK...I have a JDM H22, which I have HEARD has somewhat shorter gear ratios...so how can I tell if my speedometer is somewhat off? I have heard that the best way to tell is going by a certain RPM in 5th and seeing what the speed indicated is. Keep in mind that I am running smaller diameter rims and tires than you Prelude guys, so I am expecting it to be a bit off, but not by much.

Also, I have a question about the speedometer calibrating process. IF I were to get the speedometer calibrated...would that change the tachometer's readings at all? I am wondering if the tachometer reads the way it does based on the speedometer's reading, or if the tachometer operates on it's own and doesn't have anything to do with the speedometer or not. I ask this because I don't wanna calibrate the speedometer and then have the tach be off so I rev too high (I don't have a rev limiter) and damage something.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by explosive &raquo;</TD></TR><TR><TD CLASS="quote">OK...I have a JDM H22, which I have HEARD has somewhat shorter gear ratios...so how can I tell if my speedometer is somewhat off? I have heard that the best way to tell is going by a certain RPM in 5th and seeing what the speed indicated is. Keep in mind that I am running smaller diameter rims and tires than you Prelude guys, so I am expecting it to be a bit off, but not by much.

Also, I have a question about the speedometer calibrating process. IF I were to get the speedometer calibrated...would that change the tachometer's readings at all? I am wondering if the tachometer reads the way it does based on the speedometer's reading, or if the tachometer operates on it's own and doesn't have anything to do with the speedometer or not. I ask this because I don't wanna calibrate the speedometer and then have the tach be off so I rev too high (I don't have a rev limiter) and damage something.</TD></TR></TABLE>

haha wrong the jdm h22a tranny has the same gear ratios as a 4th gen and even if it didn't it would not affect your speedometer. Whoever you heard this from is not so smart. The Euro-R and Type-R Accord trannies are the only ones with different ratios, I should know i have one, and no it does not affect my speedometer.

Your speedometer goes off if you are using the wrong overall tire diameter, aka the prelude expects approx 23.88 inches overall so if your rims and tires are different than that your speedo will be off.

 

if you want to find out how off they are, do exactly 80 down a road that it posted 45, and hope a cop clocks you. Find out the speed on the ticket, and there's your answer!

 

OK...so I need to calibrate my speedometer clearly since I am using tires that are a bit too small...and I know this is throwing my reading off quite a bit. How can I make the speedometer read a lower MPH than it is now?

Because the problem is that sometimes the speedometer is indicating to me that I am going WAY faster than I really am. I assume that you would take off the gauge bezel, go driving somewhere, pop it in 5th gear at a certain RPM that you know should be a certain MPH and then carefully rotate the needle backward?

 

ttt

 

I think you'll break the needle if you do that. Use proper size tires You can see how much you are off here

http://www.miata.net/garage/tirecalc.html

stock tire size is 205/55/15